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Geological Audit Services, Inc. <br /> �-� 1803 W March Lane, Suite A• Stockton, CA 95207 • (209) 956-0264• FAX (209) 956-0700 <br /> — 18 November 1991 <br /> . a— (GeoAudit CV 43C4-1.1) <br /> Ms. Margaret Lagorio, RENS <br /> Public Health Services - San Joaquin County <br /> Environmental Health Division <br /> P.O. Box 2009 - <br /> Stockton, California 95201 <br /> Subject: Progress Report for Vacuum Extraction at Genova Bakery - <br /> 749 North Sierra Nevada, Stockton, California <br /> Dear Ms. Lagorio: <br /> In accordance with the request of our client, the Estate of Angelo <br /> Rolleri, we have prepared this report to update you on the progress <br /> of the mitigation project up to 15 November 1991 at the referenced <br /> address. <br /> Upon receipt of a permit to operate a vapor extraction system from <br /> the San Joaquin Valley Unified Air Pollution Control District <br /> (Order No. 91-61 dated 8 August 1991) the vacuum extraction project <br /> at the referenced address was initiated on 15 August 1991. After <br /> initial ad3ustment and scheduled maintenance, the vacuum extraction <br /> system has been operating practically 24-hours/day, extracting an <br /> average of 60 cubic feet per minute (cfm) of vapor from the well . <br /> During the first 96 hours the unit was operated by the recovered <br /> vapor only. After that period, supplemental fuel (natural gas) has <br /> been added as needed. As of 15 November 1991, the vacuum extraction <br /> unit is in operation for approximately 1, 500 hours. <br /> Organic vapor (OV) concentrations are measured on weekly basis at <br /> the inlet, pre-catalyzer outlet and post-catalyzer with a photo- <br /> ionization detector (PID: Thermo Environmental 580A, 10 . 0 eV lamp <br /> energy, calibrated to isobutylene) . The recovered OV concentrations <br /> from the well prior to combustion (y-axis) are plotted versus time <br /> (x-axis) on Figure 1. During organic vapor readings, fluctuations <br /> were noted in the concentration of hydrocarbon vapors. For <br /> recording purposes, however, the highest levels were consistently <br /> recorded. <br /> A destruction rate of greater than 90% has been achieved throughout <br /> the entire operational period. Organic vapor records demonstrated <br /> an initial increase followed by an overall decline. Currently, the <br /> average OV readings in the last 5 monitoring periods is 1, 400 ppm <br /> as isobutylene, representing approximately 65% of the (average) <br /> • highest readings of 2, 200 ppm. These data indicate an on-going <br /> venting progress. <br /> 0 <br /> Environmental Services• Hydrogeology•Geotechnical Services <br />